{"id":"CVE-2024-50217","summary":"btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()\n\nMounting btrfs from two images (which have the same one fsid and two\ndifferent dev_uuids) in certain executing order may trigger an UAF for\nvariable 'device-\u003ebdev_file' in __btrfs_free_extra_devids(). And\nfollowing are the details:\n\n1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs\n   devices by ioctl(BTRFS_IOC_SCAN_DEV):\n\n             /  btrfs_device_1 → loop0\n   fs_device\n             \\  btrfs_device_2 → loop1\n2. mount /dev/loop0 /mnt\n   btrfs_open_devices\n    btrfs_device_1-\u003ebdev_file = btrfs_get_bdev_and_sb(loop0)\n    btrfs_device_2-\u003ebdev_file = btrfs_get_bdev_and_sb(loop1)\n   btrfs_fill_super\n    open_ctree\n     fail: btrfs_close_devices // -ENOMEM\n\t    btrfs_close_bdev(btrfs_device_1)\n             fput(btrfs_device_1-\u003ebdev_file)\n\t      // btrfs_device_1-\u003ebdev_file is freed\n\t    btrfs_close_bdev(btrfs_device_2)\n             fput(btrfs_device_2-\u003ebdev_file)\n\n3. mount /dev/loop1 /mnt\n   btrfs_open_devices\n    btrfs_get_bdev_and_sb(&bdev_file)\n     // EIO, btrfs_device_1-\u003ebdev_file is not assigned,\n     // which points to a freed memory area\n    btrfs_device_2-\u003ebdev_file = btrfs_get_bdev_and_sb(loop1)\n   btrfs_fill_super\n    open_ctree\n     btrfs_free_extra_devids\n      if (btrfs_device_1-\u003ebdev_file)\n       fput(btrfs_device_1-\u003ebdev_file) // UAF !\n\nFix it by setting 'device-\u003ebdev_file' as 'NULL' after closing the\nbtrfs_device in btrfs_close_one_device().","modified":"2026-04-02T12:21:20.855411Z","published":"2024-11-09T10:14:28.798Z","related":["USN-7276-1","USN-7277-1","openSUSE-SU-2024:14500-1","openSUSE-SU-2025:14705-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/50xxx/CVE-2024-50217.json"},"references":[{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2025/04/10/4"},{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2025/04/10/5"},{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2025/04/10/6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/47a83f8df39545f3f552bb6a1b6d9c30e37621dd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aec8e6bf839101784f3ef037dcdb9432c3f32343"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/50xxx/CVE-2024-50217.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-50217"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"142388194191a3edc9ba01cfcfd8b691e0971fb2"},{"fixed":"47a83f8df39545f3f552bb6a1b6d9c30e37621dd"},{"fixed":"aec8e6bf839101784f3ef037dcdb9432c3f32343"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-50217.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}